This project develops and fieldtests a prototype software/hardware assessment package to support assistive technology assessment personnel responsible for selection of appropriate control interface devices for persons who have difficulty interacting with their environment. This population includes individuals with learning, intellectual, or physical disabilities; very young persons; and/or elderly persons. The Control Interface Assessment System (CIAS) includes software designed to measure critical characteristics of the client's ability to interact with a variety of available and potentially useful control interface devices such as touch keyboards and adaptive switches. The Phase I prototype CIAS system will be compatible with standard microcomputers and utilize two specially designed control interface devices: a Membrane Keyboard Simulator (MKS) and a Universal Adjustable Microswitch (UAS). These devices will connect to a microcomputer and be operated by the client following a series of standardized test sequences under software control using visual, auditory, and kinesthetic prompting. CIAS is intended to greatly improve the accuracy of assessment procedures for determining appropriate devices for environmental manipulation and control. A second benefit of perhaps greater value is the capability to simulate a wide array of expensive, highly specialized control interface devices prior to a decision to acquire any particular one.